Figure 1.10: This graph shows the Atomic Radius (distance from the center of the nucleus to
the valence (outer) level of electrons) vs Atomic Number, displaying the trend in atomic radius
for the first 40 elements in the periodic table.
Description: Each successive period is displayed in a different section of the atomic number
(x-axis), ex. 1-10, 11-20, 21-30, etc. As the atomic number increases within a period, the atomic
radius decreases. To put simply, the peaks represent group 1 or alkali metals and the troughs
represent group 18 or halogens.
DISCUSSION QUESTIONS: (Please answer on a separate document/paper)
PART ONE:
1. All the elements found at the peaks of your graph should fall into the same group.
a. What is the group number?
Group 1
b. What is the name of this group?
Alkali metals
2. All the elements found at the troughs of your graph should fall into the same group.
A. What is the group number?
Group 18
b. What is the name of this group?
Halogens
3. What appears to be the trend in the size of elements (atomic radii) as you move down a
group? Ex) What happens to the size of atoms as you move from Li⮴Na⮴K⮴Rb⮴Cs?
Size increases
4. a. What appears to be the trend in the size of elements as you go from left to right across a
period/row on the periodic table? Ex) What happens to size as you move from
Li⮴Be⮴B⮴C⮴N etc.
Size decreases
b. There is one exception to this trend. Where is it?
Neon to sodium
5. Based on the data of your graph, estimate/predict what the atomic radius for Cesium
(atomic number 55) would be.
270
Figure 1.11: This graph shows the Ionization energy (the energy required to REMOVE the most
weakly held electron from a neutral gaseous atom) vs Atomic Number, displaying the trend in
ionization energy for the first 40 elements in the periodic table.
Description: As the number of shells increases for an element so does the ionization energy. In
the graph the peaks are the elements in group 18 or halogens and on the troughs are the
elements in group 1 or alkali metals.
DISCUSSION QUESTIONS: (Please answer on a separate document/paper)
PART TWO:
1. All the elements found at the peaks of your graph should fall into the same group.
a. What is the group number?
18
b. What is the name of this group?
Halogens
c. Is this the same group that had the highest atomic radii in Part One?
no
2. All the elements found at the troughs of your graph should fall into the same group.
1
a. What is the name of this group?
Alkali metals
b. Suggest a reason why this group would have low ionization energies. In other words,
why does it not take much energy to tear a valence electron from these elements?
The nucleus's attraction to electrons increases with the number of protons it contains.
Electron removal is more challenging due to this increased attraction.
3. What is the trend in the first ionization energies as you move down a group?
The ionization energy decreases as an addition of a shell.
4. What is the trend in the first ionization energies as you go from left to right across a
period/row on the periodic table?
The ionization energy increases as the proton number increases but with the same number
of shells as the first group, when moving left to right.
5. Based on the data of your graph, estimate/predict what the first ionization energy for
Cesium (atomic number 55) would be.
0.376 Kg/Mol